Is there a way for particles on a curve guide to collide?
To keep particles at the end of Curve Guide you can change Settings &gt; Free to 0.300. But since particles Life Time is given to use this number of frames to get from start to end of curve (and has influence to its speed) it was quite confusing what is going on there.
Blender Manual says:

Free – Fraction of particle life time, that is not used for the curve.


You can also try Curve object and under Physics enable Force Field &gt; type Curve

One of many tutorials.
Use Particles System &gt; Physics &gt; Fluid type to get volume in a pool.